A non-invasive method of detecting or screening for lung cancer in a subject specimen is provided. The method includes detecting elevated levels of one or more carbonyl-containing volatile organic compounds (VOCs) that are biomarkers for lung cancer in exhaled breath from the subject specimen. The method may further include obtaining exhaled breath from the subject specimen; forming adducts of the carbonyl-containing VOCs with a reactive chemical compound; quantifying the adducts of the carbonyl-containing VOCs to establish a subject value for each of the adducts; and comparing each subject value to a threshold healthy specimen value for each of the adducts of the carbonyl-containing VOCs. One or more subject values at quantities greater than threshold healthy specimen values are also useful for screening for lung cancer in the subject specimen.